The sense of smell is an early warning system for the detection of environmental hazards such as spoiled food, natural gas leaks, smoke, or airborne pollution. Smells also play an important role in quality of life, imparting the flavor of foods and beverages. The long- term objective of this proposal is to understand the nature of odor coding at the receptor level. Currently, little is known about how changes in the receptor activation pattern alter olfactory perception. In the research proposed here, we use next-generation sequencing techniques, heterologous expression systems, and human psychophysics to understand the links between receptor genotype, receptor function and olfactory perception. Learning the rules for transforming receptor activity into perception will advance our understanding of odor coding.